The present invention relates to test tubes, and in particular to test tubes that include machine readable encoded markings to uniquely identify the test tube.
It is known to apply a marking to a test tube to uniquely identify the test tube. For example, PCT Application designated WO 98/05427, published on Feb. 12, 1998 and entitled xe2x80x9cTest Tube With Optically Readable Codingxe2x80x9d discloses a test tube that includes a carrier portion comprising an optically readable coding, such as a dot code. The carrier portion is attached to the bottom of the tubular container, which is the main body of the test tube. For example, this PCT application discloses that the carrier portion may be fixed to the tubular container by a retaining lug or recess, or by being glued, stuck or pressed onto the tubular container.
A problem with this design is that the carrier portion and the tubular container are physically separate devices. In use the carrier may become separated from the tubular container, which defeats the purpose of providing each tube with identification information. In addition, using separate components leads to additional manufacturing costs and complexity.
U.S. Pat. No. 5,777,303 also discloses employing a carrier portion that is affixed to a test tube, and includes an electronic label that comprises an integrated circuit. However, the design disclosed in this patent also has the inherent problem that the carrier portion and tubular portion are physically separate devices.
Therefore, there is a need for an improved test tube that facilitates marking each tube with an identification code uniquely representative of the tube.
Briefly, according to an aspect of the present invention, a test tube comprises a tube body of unitary construction comprising an enclosed sidewall and an integral bottom surface that together define a tubular container having an open top. The bottom has a concave interior and a planar exterior surface upon which machine readable data is encoded within a multi-layered opaque coating that is deposited onto the planar exterior surface to uniquely identify the test tube.
The machine readable data is preferably an open (i.e., non-proprietary) data matrix code. This code is applied to the test tube by first depositing a multi-layer coating onto the planar exterior of the tube bottom. The multi-layer coating may include a first layer of opaque material that is deposited onto the planar exterior surface, and a second layer of opaque material of a different color that is deposited onto the first layer. The machine readable code is formed in the multi-layered coating by removing portions of the second layer.
In a preferred embodiment, the first and second layers of the multi-layer coating are applied to the exterior surface by thermal transfer (e.g., hot stamping), and select regions of the second layer are removed with a coherent light source (e.g., a laser) to define the machine readable data matrix code.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings.